Dielectric ceramic capacitors, with the advantages of high power density, fast charge-discharge capability, excellent fatigue endurance, and good high temperature stability, have been acknowledged to be promising candidates for solid-state pulse power systems. This review investigates the energy storage performances of linear dielectric, relaxor ferroelectric, and antiferroelectric from the viewpoint of chemical modification, macro/microstructural design, and electrical property optimization. Research progress of ceramic bulks and films for Pb-based and/or Pb-free systems is summarized. Finally, we propose the perspectives on the development of energy storage ceramics for pulse power capacitors in the future.

Microstructure characteristics, phase transition, and electrical properties of (Na0.535K0.485)0.926Li0.074(Nb0.942Ta0.058)O3 (NKN‐LT) lead‐free piezoelectric ceramics prepared by normal sintering are investigated with an emphasis on the influence of sintering temperature. Some abnormal coarse grains of 20–30 μm in diameter are formed in a matrix consisting of about 2 μm fine grains when the sintering temperature was relatively low (980°C). However, only normally grown grains were observed when the sintering temperature was increased to 1020°C. On the other hand, orthorhombic and tetragonal phases coexisted in the ceramics sintered at 980°–1000°C, whereas the tetragonal phase becomes dominant when sintered above 1020°C. For the ceramics sintered at 1000°C, the piezoelectric constant d33 is enhanced to 276 pC/N, which is a high value for the Li‐ and Ta‐modified (Na,K)NbO3 ceramics system. The other piezoelectric and ferroelectric properties are as follows: planar electromechanical coupling factor kp=46.2%, thickness electromechanical coupling factor kt=36%, mechanical quality factor Qm=18, remnant polarization Pr=21.1 μC/cm2, and coercive field Ec=1.85 kV/mm.

A slim P–E loop with delayed early polarization saturation is more beneficial for enhancing energy storage performance.

BaTiO 3 ceramics with different domain sizes were prepared by spark plasma sintering (SPS) and normal sintering (NS) using hydrothermally synthesized 100 nm and 500 nm powders. It was found that their piezoelectric constant d 33 shows great dependence on the size of ferroelectric domains. A high d 33 up to 416 pC/N was obtained in the SPSed ceramics derived from 100 nm powders, whose domain width was identified <50 nm by transmission electron microscopy (TEM). However, the d 33 values are 216 and 193 pC/N, respectively for the BaTiO 3 ceramics prepared by SPS using 500 nm powders and by NS using 100 nm powders, whose microscale domains can be observed by optical microscopy.

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Fine-grained Pb-free (Na0.535K0.485)0.95Li0.05(Nb0.8Ta0.2)O3 (NKLNT) piezoceramics prepared by spark plasma sintering (SPS) technique was used to fabricate NKLNT/epoxy 1–3 composites with a modified dice–fill method. Because of its good machinability, SPSed NKLNT ceramic rods could be miniaturized to a lateral width of 50 µm. After lapping down to 56 µm in thickness, the composite was used to fabricate an ultrasonic transducer as the active piezoelectric element. This composite transducer showed a bandwidth at −6 dB nearly 90%at a center frequency of 29 MHz, demonstrating that this Pb-free composite thick film is very promising for the fabrication of high-frequency ultrasonic transducers in medical imaging applications.

Ba 0.3 Sr 0.7) x (Bi 0.5 Na 0.5) 1-x TiO 3 (BS x BNT, x = 0.3-0.8) ceramics were prepared to investigate their structure, dielectric and ferroelectric properties. BS x BNT ceramics possess pure perovskite structure accompanied from a tetragonal symmetry to pseudo-cubic one with the increase of x value, being confirmed by X-ray diffraction (XRD) and Raman results. The T m corresponding to a temperature in the vicinity of maximum dielectric constant gradually decreases from 110 ℃ (x = 0.3) to-45 ℃ (x = 0.8), across T m = 36 ℃ (x = 0.5) with a maximum dielectric constant (ɛ r = 5920 @1 kHz) around room temperature. The saturated polarization P s gradually while the remnant polarization P r sharply decreases with the increase of x value, making the P-E hysteresis loop of BS x BNT ceramics goes slim. A maximum difference between P s and P r (P s-P r) is obtained for BS x BNT ceramics with x = 0.5, at which a high recoverable energy density (W rec = 1.04 J/cm 3) is achieved under an applied electric field of 100 kV/cm with an efficiency of  = 77%. Meanwhile, the varied temperature P-E loops, fatigue measurements, and electric breakdown characteristics for the sample with x = 0.5 indicate that it is promising for pulsed power energy storage capacitor candidate materials.